Combination axial-flow fan

ABSTRACT

A high-performance low-noise combination axial-flow fan includes a fan hub that has a center connection portion for the connection of a fan motor shaft and a mounting groove extending around the periphery, and fan blades each having a wedge block disposed at the inner end for fastening to the mounting groove to secure the respective fan blade to the fan hub in such a manner that no gap is seen between each two adjacent fan blades when viewed from the front side.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a fan and, more particularly, to a combination axial-flow fan for use in an electronic product for forced air convection cooling.

(b) Description of the Prior Art

Regular cooler modules are designed for use in electronic and photoelectric products to expel waste heat. A typical conventional cooler module is comprised of a passive heat dissipation device and an active heat dissipation device. A passive heat dissipation device can be a heat sink extruded from copper or aluminum and having multiple radiation fins. An active heat dissipation device can be an axial-flow fan that forces surrounding air to cause convection, thereby lowering the surrounding temperature. A typical conventional axial-flow fan comprises a fan hub 10 and multiple blades 20 integrated into and extending around the periphery of the fan hub 10 (see FIG. 6). By means of controlling a motor to rotate the fan hub 10, the blades 20 produce a wind pressure, achieving force-air cooling. Because the parameters of 3D camber, angle, number, and radius of the fan blades determine the wind pressure, pressure amount, and noise levels, it is the optimum design where there is no gap structure seen in the fan blades when viewed from the front side, i.e., the front edge of one fan blade blocks the rear edge of another adjacent fan blade. However, this design is not applicable due to technical problems in molding technology. A partial fan blade overlapping arrangement will result in a mold stripping problem after injection molding. Therefore, there is a gap d′ between each two adjacent fan blades 20 (see FIG. 6), allowing removal of the molded fan from the mold. The presence of this gap d′ is one of the major reasons of the production of wind noise. It also tends to cause an insufficient wind pressure problem, which presents difficulties in satisfying heat dissipation requirements of modern electronic devices.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances in view. It is therefore one object of the present invention to provide a combination axial-flow fan, which has the fan hub and the fan blades separately made and then assembled together so that the front edge of one fan blade is suspended above the rear edge of another fan blade, no gap is seen between each two adjacent fan blades when viewed from the front side, and has high wind pressure, high wind capacity, and low noise level characteristics.

To achieve this and other objects of the present invention, the combination axial-flow fan comprises a fan hub and a set of fan blades. The fan hub and the fan blades are separately made and then assembled together. The fan hub comprises a center connection portion for the connection of a fan motor shaft, and a mounting groove extending around the periphery. The mounting groove is an endless groove extending around the periphery of the fan hub near the front side of the fan hub, having an open side that extends in direction toward the rear side of the fan hub. Each fan blade comprises a wedge block disposed at the inner end. The wedge block has a top protruding engaged into the mounting groove of the fan hub, and a bottom locating groove for the mounting of a retaining ring to secure the fan blades to the periphery of the fan hub. Further, the fan hub comprises a set of positioning teeth arranged around the periphery, and the wedge block of each fan blade comprises a set of positioning teeth for engagement with the positioning teeth of the fan hub. Further, the wedge block of each fan blade comprises a retaining flange disposed at one lateral side and a retaining groove disposed at the other lateral side. By means of engaging the retaining flange of the wedge block of one fan blade into the retaining groove of the wedge block of another fan blade, the fan blades are thus fastened together.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a combination axial-flow fan according to the present invention.

FIG. 2 is an assembly view of the combination axial-flow fan according to the present invention.

FIG. 3 is a sectional view of a part of the present invention, showing the retaining flange of the wedge block of one fan blade fastened to the retaining groove of the wedge block of another fan blade.

FIG. 4 is a sectional elevation of the combination axial-flow fan according to the present invention.

FIG. 5 is a front view of the combination axial-flow fan according to the present invention.

FIG. 6 is a schematic front view of an axial-flow fan according to the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIGS. 1 and 2, a combination axial-flow fan in accordance with the present invention comprises a fan hub 1 and a plurality of fan blades 2. The fan hub 1 and the fan blades 2 are separately molded from plastics by means of injection molding, and then assembled together for use as an active heat dissipation device for the cooling of an electronic product.

Referring to FIGS. 1 and 2 again, the fan hub 1 may be made in any of a variety of shapes. According to the present preferred embodiment, the fan hub 1 is shaped like a round cap, having a front side 12, a rear side 14, a center connection portion 11 at the center of the front side 12 for the connection of the shaft of a fan motor (not shown), an endless mounting groove 13 extending around the periphery near the front side 12 and having its open side extending in direction from the front side 12 toward the rear side 14, and positioning teeth 15 arranged around the periphery near the rear side 14. The positioning teeth 15 may be made in any of a variety of shapes. According to the present preferred embodiment, the tooth form of the positioning teeth 15 shows a V-shaped cross section.

Referring to FIG. 3 and FIGS. 1 and 2 again, the fan blades 2 are identical in shape, each having a front edge 21, a rear edge 22, an outer edge 23 and an inner edge 24. There are no particular limitations on the 3D camber and geometric shape of the fan blades 2. The 3D camber and geometric shape of the fan blades 2 can be modified to achieve optimum performance subject to aerodynamics. Each fan blade 2 further has a wedge block 25 connected to the inner edge 24 and fitting the circular shape of the periphery of the fan hub 1. The wedge block 25 has a top protrusion 251 for engagement into the endless mounting groove 13 of the fan hub 1, a number of positioning teeth 252 formed on the inner side for engagement with the positioning teeth 15 of the fan hub 1, a female retaining portion, for example, a retaining groove 253 disposed at one lateral side, and a male retaining portion, for example, retaining flange 254 disposed at the other lateral side. Further, the positioning teeth 252 may be made in any of a variety of shapes. According to the present preferred embodiment, the tooth form of the positioning teeth 15 shows a V-shaped cross section. By means of forcing the retaining flange 254 of the wedge block 25 of one fan blade 2 into engagement with the retaining groove 253 of the wedge block 25 of another fan blade 2 (see FIG. 3), the fan blades 2 are fastened together around the periphery of the fan hub 1 (see FIG. 2). The wedge block 25 further has a bottom locating groove 255. When the fan blades 2 are fastened together and secured to the periphery of the fan hub 1, an O-shaped or C-shaped retainer ring 3 is fastened to the bottom locating grooves 255 of the wedge blocks 25 of the fan blades 2, securing the fan blades 2 and the fan hub 1 firmly together.

Referring to FIG. 3 again, the retaining groove 253 has an expanded portion, and the retaining flange 254 has an expanded distal end fitting the expanded portion of the retaining groove 253. By means for inserting the retaining flange 254 of the wedge block 25 of one fan blade 2 into the retaining groove 253 of the wedge block 25 of another fan blade 2, the fan blades 2 are connected together and prohibited from transverse displacement relative to one another. After installation of the retainer ring 3 in the bottom locating grooves 255 of the wedge blocks 25 of the fan blades 2, the connection stability between the fan blades 2 and the fan hub 1 is enhanced.

After installation, as shown in FIG. 2, the fan blades 2 are radially disposed around the fan hub 1 and equiangularly spaced from one another. Thereafter, the center connection portion 11 of the fan hub 1 is fastened to the shaft of a fan motor (not shown) and then the assembly of the fan hub 1 and fan blades 2 is mounted with the fan motor in a rack, constituting an electric fan for use in a cooler module.

Because the fan hub 1 and the fan blades 2 are separately molded from plastics and then assembled together, fan blades having different 3D camber and geometric shape features can be selectively used with one same fan hub to constitute different combination axial-flow fans for different applications to satisfy different cooling requirements, thereby lowering the mold cost.

Referring to FIGS. 4 and 5, because the fan blades 2 and the fan hub 1 are separately made and then assembled together, it is practical to constitute a high-performance axial-flow fan having low noise level, i.e., the front edge 21 of one fan blade 2 is suspending above the rear edge 22 of another adjacent fan blade 2 so that no gap is seen between each two adjacent fan blades 2 when the axial-flow fan is viewed from the front side (see FIG. 5), however, the desired wind tunnel D is still maintained in between each two adjacent fan blades 2. This fan structure is not achievable by conventional fan designs. By means of the application of the present invention, this fan structure is easily attainable.

Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. 

1. A combination axial-flow fan, comprising: a fan hub, said fan hub comprising a center connection portion for the connection of a fan motor shaft and a mounting groove extending around the periphery thereof; and a plurality of fan blades, each said fan blade comprising a wedge block disposed at an inner end thereof for fastening to said mounting groove to secure the respective fan blade to said fan hub.
 2. The combination axial-flow fan as claimed in claim 1, wherein said mounting groove is a continuous groove extending all around the periphery of said fan hub near a front side of said fan hub, having an open side extending in a direction toward a rear side of said fan hub; and the wedge block of each said fan blade is smoothly arched to fit the periphery of said fan hub, having a top protrusion for engagement into said mounting groove of said fan hub and a bottom locating groove for mounting a retaining ring to secure said fan blades to the periphery of said fan hub.
 3. The combination axial-flow fan as claimed in claim 2, wherein said fan hub comprises a set of positioning teeth arranged around the periphery thereof; and the wedge block of each said fan blade comprises a set of positioning teeth for engagement with the positioning teeth of said fan hub.
 4. The combination axial-flow fan as claimed in claim 2, wherein the wedge block of each said fan blade comprises a retaining flange disposed at one lateral side thereof and a retaining groove disposed at an opposite lateral side thereof, the retaining flange of the wedge block of one said fan blade being engaged with the retaining groove of the wedge block of an adjacent said fan blade.
 5. The combination axial-flow fan as claimed in claim 4, wherein said retaining groove of each said wedge block has an expanded portion, and said retaining flange of each said wedge block has an expanded distal end fitting the expanded portion of said retaining groove. 